Disclosure: I'm fairly dubious that we as a modern discourse fully understand the reality of life, and propagation, shaping of life.

I have a lot of reservations. And I often times find myself rather disgusted by the attitude and approach of many people in the scientific worldview.

That being said, I do believe there are some interesting numbers out there about how much more efficient dairy is than just simply eating your animals. It also produces a relatively large amount of fat, which is is incredibly important (for your brain, and much else) and is one of the more difficult parts of a diet to attain in most ecosystems.

There could possibly also be advantages related to the ease of lactobacillus fermentation.